Mineralocorticoid-like steroids other than aldosterone have been postulated to be elevated in low-renin "essential" hypertension and therefore to contribute to the elevated blood pressure in the disease. In the proposed studies we plan to develop a radioreceptor assay for quantifying plasma mineralocorticoid activity due to steroids which act through the renal aldosterone receptor by measuring the ability of plasmas to inhibit the binding of radioactive aldosterone by these receptors.